An old test for ovarian cancer is showing new promise. Doctors have been debating the value of a blood test called CA-125 for decades. Ovarian cancer is often a killer because it is hard to detect at a treatable stage. That’s why researchers have been seeking a marker that might improve early detection. CA-125 is a protein that may be elevated in patients with certain kinds of cancer. A single measurement, however, has been unreliable. Many different factors affect its levels, and there is no reliable threshold to indicate ovarian cancer.
A new study from M.D. Anderson tracked annual measurements of CA-125 in over 4,000 healthy postmenopausal women for more than a decade. If their blood levels rose rapidly, they were retested on a more frequent basis (every three months). If the levels jumped dramatically the women were referred for ultrasound. Anything suspicious on this exam led to exploratory surgery.
Of the roughly 4,000 women, 117 underwent transvaginal ultrasound. Ten of those had exploratory surgery and four out of the ten were found to have early-stage ovarian cancers. Prompt treatment appears to have been successful in these four cases. Before recommending routine CA-125 screening for ovarian cancer, the researchers plan to review results from a large British study in 2015.
That seems sensible, since finding 4 cases of ovarian cancer required 4,000 women to be screened every year, more than a hundred women to undergo transvaginal ultrasound and six women to submit to unnecessary surgery, which is not without risk. Previous studies of ovarian cancer screening have been unrewarding. Even though treating CA-125 more like PSA for cancer detection may be better than current diagnostic approaches, it still is far from ideal.
